Superconducting transition at 38 K in insulating-overdoped La2CuO4-La1.64Sr0.36CuO4 superlattices: Evidence for interface electronic redistribution from resonant soft x-ray scattering

TL;DR

This study uses resonant soft x-ray scattering to reveal that in La2CuO4-La1.64Sr0.36CuO4 superlattices, holes migrate to LCO layers, enabling superconductivity at 38 K despite non-superconducting constituents.

Contribution

It demonstrates that RSXS can effectively detect electronic redistribution at oxide interfaces, linking hole doping to interface-driven superconductivity.

Findings

Holes redistribute from LSCO to LCO layers.

LCO layers are optimally doped and drive superconductivity.

Superlattice exhibits superconductivity at 38 K despite non-superconducting constituents.

Abstract

We use resonant soft x-ray scattering (RSXS) to quantify the hole distribution in a superlattice of insulating La2CuO4 (LCO) and overdoped La_{2-x}Sr_{x}CuO4 (LSCO). Despite its non-superconducting constituents, this structure is superconducting with T_{c}=38 K. We found that the conducting holes redistribute electronically from LSCO to the LCO layers. The LCO layers were found to be optimally doped, suggesting they are the main drivers of superconductivity. Our results demonstrate the utility of RSXS for separating electronic from structural effects at oxide interfaces.